Romain Grosjean is confident Lotus' worst days are behind it this season as he hopes to build on his improved performance at the Chinese Grand Prix.

Grosjean looked set for a top-ten finish at Shanghai but a gearbox problem forced him to retire, maintaining Lotus' pointless record this year. However, even during the low points this year, Grosjean said he never lost faith in his team.

"I always believed there was potential that we could see on paper, but we didn't find the key to unlock that potential until we got to China and made the first step in that direction," he said. "Some days have been more difficult than others and I think Bahrain testing was one of them because we were coming from a difficult weekend and we had so few laps [at the test]. Of course I'm a human being and I have emotions, so I was a bit down on the day but you go back home and you work.

"In China we were going in the right direction and we know that the wind tunnel is not upside down, so there's no reason that we see potential there and don't see it on track. It was small things to get at and at the end of the lap they will make a big difference."

Grosjean said his understanding of the car had improved since China and he would be making set-up changes for this weekend.

"It won't be a complete change, but we have brought a few new bits to the car and set-up-wise it is quite different even from Shanghai, so I do hope that helps us go in the right direction. If that's the case we can certainly get some good tenths in our pocket. It was not one thing, it was getting the suspension in the right area for the new tyres, understanding a little bit more the aerodynamics, how the floor is working and the wings."

Asked if points are possible this weekend, he said: "I hope so. China I probably could have had one point that would have been the toughest point to pick up ever but I didn't finish the race. Here, hopefully we will finish the race and we get some. It's a small thing but it's a good reward for what we are doing at home."